E-arc thermostat features

[kaziel]

Hi guys I'm wondering is any one of you is using e-arc setup? If so what kind of thermostat you have? Can you also suggest any possible features that you miss on your setup? I'm thinking about adding e-arc features to my VM still and I'm trying to find quality parts for that system.

[still_stirrin]

Sorry for my ignorance...but what the heck is "e-arc"?

[kaziel]

http://homedistiller.org/forum/viewtopi ... =17&t=7969

[Kegg_jam]

Try rubber duck.

He was into arc's I believe. Not sure about electronic automatic reflux control though.

[kaziel]

I was expecting more feedback. I find this solution really interesting and I thought that many of you are using it. From what I saw on the internet I've come up with following:

• Temp measure resolution 0.1deg C, temp range 0-110 deg C
• 0 hysteresis (in example valve should be open only at 78,2C and close on other temperatures).
• manual operation for taking off heads first then hold button to hold temperature on which you want to collect hearts
• output switch/relay/contactor in SPDT configuration
• programmable alarm with buzzer
• error indication after hold temperature can't be established after programmable amount of time
• powered from mains
• stainless temp probe
• probe failure detection

I know that probably I won't find anything like that but please help me make this list bigger eventually I think I will build one.

[rad14701]

The primary reason you don't see more members using ARC or E-ARC is that automation isn't required and can lead to leaving a still unattended... As you have likely read during your ARC research, most authors allude to walking away from the still, leaving it unattended, for extended periods of time... We consider this a dangerous concept due to safety concerns... Not to mention that it can take a considerable amount of work to fine-tune an ARC setup for optimal performance...

[kaziel]

Hi Rad, I'm aware of the fact that you never want to leave your still unattended. I'm using digital thermometer on still already so I though about adding some extra features to it. BTW there are a lot internet shops that are selling semi or full automatic stills but me I'm always trying to keep things safe just like to experiment a little.

[still_stirrin]

Got it ... "electric (solenoid valve) automated reflux control" ... E-ARC.

It uses a tall column (approaching 2m) with a LM takeoff and a VM takeoff to concentrate the heads at the top, leaving the hearts fractionated at the VM outlet. The top reflux condenser is "automated" as a CM using a temperature sensor with a flow control valve for the cooling water. Original designs utilized Harry's cross condenser (because it is "geometrically" appropriate for such a "intimidatingly" tall column).

It is most effective for continuous processing, not batch processing like most of us hobbiests do.

All good reading. Thanks for the tips.
ss

[still_stirrin]

I found this very interesting from Snuffy's post:

The hassle is that there are multiple azeotropes of different congeners -- methanol being the most outstanding example. It forms azeotropes with both ethanol and higher alcohols, so it has concentration peaks in both the heads AND the tails. The myth of methanol being entirely in the heads is wrong.

The presence of congeners means the usual diagram showing vapor/condensate concentrations is badly misleading because that diagram is based on theoretical Rayleigh binary distillation: only water and ethanol being present. If that was the case, there wouldn't be any heads or tails, it would be all heart and only the %abv would vary over the run.

The stumbling block is the upper limit of about 20 or so column diameters before channeling becomes a problem in a packed column. Industrial packed columns rarely go above 20 diameters in height without resorting to special measures (rechanneling collars, multiple reflux, etc.) My rough guess is that the TEP (theroretical effective plates) in most mesh columns is about 2-4 column diameters...

I think that the relative length of column running cooler than the h2o/EtOH azotrope condensation point would be an indicator of the ability to keep heads out of the product takeoff in a VM still. It should be possible to design an experiment to test this.

[kaziel]

After many hours of thinking about it I think will also add:

• 12V power supply as alternative + it can also be used to power solenoid
• Data logging (temp with time-stamp) probably on sd card
• ability to use analog probe (pt100-pt1000) for other temperatures beside Earc takeoff
• offset calibration (ice bath or boiling water)

[kaziel]

Hi again I will paste a quick sketch of what I have in mind (please don't laugh to much it was done in bus on my way to work)
https://drive.google.com/open?id=0B2WsW ... lNvSlZRUW8
Basicly I have three thermo-ports in column
1. In the bottom - this will be used to turn cooling water ON
2. 30cm belowe take of turn - this will be used to control reflux - most precise one
3. in the tom of VM - this will be used for any failure detection - this will cut power to phase angle controller. I have 250V 25A contactor for that

I will buy SS PTFE seal solenoid in next few weeks. For cooling water control I will go with brass or plastic one. Both solenoids will be normally closed. Probably I will look for 12V ones.

I think that flow chart of whole process can look like this:
1. Power up controller whit eArc thermo
2. Then Tbot>60C, start cooling water flow (power will be adjusted manually by me)
3. Open product solenoid - > take heads off (after column stabilization) - after I'm satisfied with product maintain collecting temperature
4. Ttakeoff = collecting temp -> product solenoid on, Ttakeoff > collecting temp -> product solenoid off wait for example 5min sample temp again if ok open solenoid if not wait another 5 min is not ok whole process is off, power off controller, close cooling water solenoid, buzz for End of process.

Let me know what you think